After extensive consultation with the local community, landholders and businesses, the Murray-Darling Basin Authority (MDBA), in partnership with Goulburn-Murray Water, will begin lowering the level of Lake Mulwala in early May 2022 to undertake waterweed control.
MDBA Executive Director, Dr Andrew Kremor said lowering the lake provided the best means of controlling the highly invasive water weed Egeria densa but it would also allow other maintenance work to be completed.
“Lowering the water level in the lake to control this invasive waterweed is a necessary operation that occurs every 3 to 5 years,” Dr Kremor said.
“Lake Mulwala is a popular water-skiing and boating spot, and the waterweed can make it difficult to launch boats, fish, swim or water ski without getting tangled in the weed.
“The last time the lake was lowered was in 2018 and since then the weed has become dense so it’s important that we act this winter to improve the condition of the lake to support the community, businesses and the health of the lake itself.
“In order to kill the waterweed, we need to expose it to the air and winter frosts which we will do by lowering the lake by 5 metres below operating level and holding that level for about a month.
“We expect to bring the lake back to its regular operating levels by early August.”
The MDBA has consulted with the local angling and water-ski clubs, irrigators, local councils, the Yorta Yorta Traditional Owners, tourism and hospitality operators, NSW and Victorian government agencies and others to confirm the best date.
“We know that Lake Mulwala, on Yorta-Yorta Country, is an important asset for recreation, tourism and local businesses and we appreciate the involvement of the community as we prepare for these works. We have consulted widely to ensure the timing and extent of the lowering can have the best results with as little impact as possible.
GMW Water Storage Services General Manager Martina Cusack said lowering the water level would expose large areas of the lakebed, allowing for a range of works to be conducted.
“We plan to use this opportunity to carry out maintenance under and around the bridge including pylon inspection, as well as lake retaining wall works and erosion repairs,” she said.
“It also offers an excellent opportunity for residents around the lake to carry out inspections and maintenance on their own infrastructure, such as jetties, boat ramps, retaining walls and pipe intakes.
“We remind lake users to consider adjusting their activities for changed water levels in late autumn and winter,” Martina Cusack said.
The period in which the lake levels remain low will be influenced by weather conditions and with the outlook of a wetter than average autumn the MDBA and Goulburn-Murray Water is keeping a close eye on conditions.
“During winter there’s a chance that heavy rainfall could produce inflows from the Ovens and Kiewa rivers or a spill from Hume Dam. In this case, some of the low-lying parts of the lake may be re-inundated earlier than planned. We will provide as much notice as possible of any change affecting Lake Mulwala,” Dr Kremor said.